could plumb
Regular verb: plumb - plumbed- plumbed

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I could plumb
you could plumb
he could plumb
we could plumb
you could plumb
they could plumb 	I could be plumbing
you could be plumbing
he could be plumbing
we could be plumbing
you could be plumbing
they could be plumbing	I could have plumbed
you could have plumbed
he could have plumbed
we could have plumbed
you could have plumbed
they could have plumbed	I could have been plumbing
you could have been plumbing
he could have been plumbing
we could have been plumbing
you could have been plumbing
they could have been plumbing	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I couldn't plumb
you couldn't plumb
he couldn't plumb
we couldn't plumb
you couldn't plumb
they couldn't plumb 	I couldn't be plumbing
you couldn't be plumbing
he couldn't be plumbing
we couldn't be plumbing
you couldn't be plumbing
they couldn't be plumbing	I couldn't have plumbed
you couldn't have plumbed
he couldn't have plumbed
we couldn't have plumbed
you couldn't have plumbed
they couldn't have plumbed	I couldn't have been plumbing
you couldn't have been plumbing
he couldn't have been plumbing
we couldn't have been plumbing
you couldn't have been plumbing
they couldn't have been plumbing	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
could I plumb?
could you plumb?
could he plumb?
could we plumb?
could you plumb?
could they plumb? 	could I be plumbing?
could you be plumbing?
could he be plumbing?
could we be plumbing?
could you be plumbing?
could they be plumbing? 	could I have plumbed?
could you have plumbed?
could he have plumbed?
could we have plumbed?
could you have plumbed?
could they have plumbed? 	could I have been plumbing?
could you have been plumbing?
could he have been plumbing?
could we have been plumbing?
could you have been plumbing?
could they have been plumbing? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
couldn't I plumb?
couldn't you plumb?
couldn't he plumb?
couldn't we plumb?
couldn't you plumb?
couldn't they plumb? 	couldn't I be plumbing?
couldn't you be plumbing?
couldn't he be plumbing?
couldn't we be plumbing?
couldn't you be plumbing?
couldn't they be plumbing? 	couldn't I have plumbed?
couldn't you have plumbed?
couldn't he have plumbed?
couldn't we have plumbed?
couldn't you have plumbed?
couldn't they have plumbed? 	couldn't I have been plumbing?
couldn't you have been plumbing?
couldn't he have been plumbing?
couldn't we have been plumbing?
couldn't you have been plumbing?
couldn't they have been plumbing?